cpufreq: interactive: Delay evaluation of notification by 1ms

Multiple migrations can happen together within short period if
scheduler is re-arranging a few tasks. In this case, it's only useful
to change frequency at the end of all migrations. Delay handling of
scheduler notification by 1ms.

Change-Id: I9ee7b1e93ce57c28919b5609c40dcde9bd14abed
Suggested-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>